This invention generally pertains to an electric battery, and in particular, to a lead battery of the type having a cell box which contains an electrolyte and an element formed from positive and negative electrodes with intervening separators, and cooling tubes which can be connected to a cooling device.
The charging of a lead battery is generally associated with a considerable increase in temperature. Such heating results not only from the charging reaction itself, which is exothermic, but predominantly from the Joule heating effect which results from the expended charging current, which is only partially utilized for electrochemical conversion. With gas-tight lead batteries there is also the consideration that the oxygen consumption which occurs during the terminal phase of charging, with overcharging at the negative electrodes, is likewise an exothermic process.
Thus, damaging temperatures are attained quite readily, particularly in connection with high performance batteries (i.e., batteries which not only discharge at high currents but which through a quick charge can be brought from a completely depleted state to a full charge within a few hours). Particularly affected are those cells which do not have a freely movable liquid electrolyte (i.e., fixed electrolytes), which through convection can contribute to a certain dissipation of heat from the elements of the cell.
In a conventional battery with an open cell architecture (e.g., large cells for vehicles), it is generally sufficient to circulate water around the cell connectors to achieve effective cooling. Alternatively, as suggested in DE-AS 24 14 758, coolant lines of corrosion-resistant plastic can be arranged within the cell so that they dip into the electrolyte for cooling purposes DE-OS No. 26 57 183 discloses a device having two chambers which communicate through connecting tubes arranged essentially within the gas compartment of the cell to permit a tempering of the liquid electrolyte portion as well as the vaporous and gaseous aggregates contained within the cell, and in which the circulation of coolant through the connecting tubes is adjusted using an appropriate valve.
However, such measures have not proven to be entirely satisfactory, particularly in connection with higher performance cells or cells with fixed electrolytes.